1. Field of the Invention
The present invention relates to an information processing terminal connected to LAN for carrying out IP communication, and, more particularly, to power control of a terminal including a function for coping with WOL (Wake On LAN).
2. Description of the Related Art
As information processing terminals such mobile terminals are provided with multifunction, how to suppress their power consumption becomes a problem. As a technology for suppressing power consumption of a terminal, there is known a technology for shifting the terminal in an operating state to a suspended state. The term “suspended” means operation for reducing power supplied to the terminal after a working state until just before the suspend state occurs is stored in a memory.
The terminal can be automatically shifted from the operating state to the suspended state by using, for example, timer processing. A flowchart of FIG. 7 shows an example of the timer processing.
In FIG. 7, when an information processing terminal in a suspended state is resumed by being actuated by a user (step C1), a suspend timer, to which a predetermined period of time is set, starts (step C2). After the timer starts, the terminal monitors a flag showing whether or not interrupt processing occurs (step C3), and the suspend timer is reset each time the interrupt processing occurs (step C4).
The information processing terminal monitors a state of the timer in parallel with monitoring of the interrupt flag (step C5), and when the time expires, that is, when the predetermined period of time has passed without occurrence of the interrupt processing after the terminal is resumed, the terminal shifts to the suspended state (step C6). A power control method making use of the timer processing is disclosed in, for example, Japanese Patent Application Laid-Open No. 2002-341979.
Further, there is conventionally known a WOL technology for resuming an information processing terminal in a suspended state from a remote place through LAN. When a terminal for coping with the WOL receives a packet, in which a particular bit train is described, from LAN, it is resumed from a suspended state. A technology as to computer processing using WOL is disclosed in Japanese Patent Application Laid-Open No. 2000-099414.
However, the information processing terminal for carrying out the suspend timer described above keeps an operating state for a predetermined period of time even if no interrupt processing occurs after it is resumed from a distant place by WOL. This means that if even there is no user who carries out response manipulation to the terminal resumed by WOL, the terminal continuously consumes power more than the suspended state until the period of time expires. This operation is not desirable from a view point of power saving.